The invention relates in general to aggregate measuring apparatus, in particular to such an apparatus which provides fractional part emptying of a measured fill of aggregate into a cement mixer and specifically to such an apparatus for measuring sand for small batches of cementitious like building material at a construction site.
Accurate mesurement and fractional part emptying of aggregate into an on-site cement mixer have long been known to be important to high quality masonry. Each batch of building material, be in concrete, mortar, plaster or other material consists of aggregate together with other consituents such as cement and water. The quality of the end product of such materials varies according among other things to the proportions of the various constituents, including the aggregate. Aggregate control is particularly difficult. Usually the aggregate is sand delivered to the site by the truck load and dumped into a pile. Frequently it is measured for a batch "by the shovel full". A worker counts the number of shovels of sand put into the mixer. The amount of sand per shovel full inevitably varies. The aggregate measure can be off by entire shovel fulls as a result of distractions or if the shovel count is otherwise lost. By contrast, control of the other constituents is usually highly accurate. They usually are added to the mixer as all of a pre-packaged accurately measured bag. The quality of a particular batch also is a function of the mixture homogeneity. It has also long been known that a more homogenous mixture is obtained if the various constituents are added in fractional parts, particularly the aggregate. It is common practice to add the aggregate of a mix in fractional parts. For example, a three cubic foot batch of mortar for standard cement block construction consisting of three cubic feet of mason's sand, one-half cubic foot of type S hydrated lime and one-half cubic foot of portland cement is commonly mixed as follows: in a standard cement mixer having a constantly rotating barrel, one-half of the sand is put into the mixer and enough water is added to form a slurry; after a short interval, all of the lime is added and water again added to maintain a slurry consistency; a short time later all of the cement and additional water is added to maintain a slurry consistency; finally, the remainder of the sand is added but this time only enough water is added to produce what is referred to as a "workable" mix. As a further illustration, it is well known that a standard mix of one part masonry cement and three parts masonry sand is properly mixed, using a standard mixer as described above, by: adding one-half of the sand plus enough water to form a slurry; after a short interval, adding all of the cement plus enough water to maintain the mix as a slurry; and, finally, after another short interval, adding the remainder of the sand, again with only enough water to produce a workable mix.
A general object of the invention is to provide an aggregate measuring apparatus.
An object of the invention is to provide a fractional part emptying aggregate measuring apparatus.
Another object of the invention is to provide an on-site aggregate measuring apparatus.